6. Garlic

"Onions and garlic belong to the genus Allium. These plants share a common toxic mechanism whereby they cause oxidative injury to cells — in particular, red blood cells. The sulfhydryl groups in hemoglobin are oxidized by sulfoxides that are present in all parts of the plant and bulbs.

"Cats have about twice as many sulfhydryl groups per hemoglobin molecule than dogs and other species, making them particularly sensitive to oxidative injury from Allium plants. Even a one-time small amount of garlic is enough to impair their ability to transport oxygen to tissues, causing injury to red blood cells that can last for months. In essence, it is a form of anemia in cats. If chronically exposed even to very low amounts over a long period of time, most cats will suffer signs of anemia."

More from this Slideshow

After interviewing veterinary toxicologist Dr. John Tegzes earlier this week, I couldn't help but ask him one more question that I'd been dying to bring up: It's been my observation that plenty of poisons tend to fly beneath most owners' radars. While chocolate, pesticides and rat poison get prime billing, others receive short shrift from the public. Which toxins make your list of the least respected pet poisons out there? Here are Dr. Tegzes' picks and thoughts:

Dr. Tegzes: "Of all the pet poisonings called into poison centers, exposure to human medications consistently tops the list. I think this is because most people don't believe that their dog or cat will eat a pill. If you've ever tried medicating your dog or cat yourself, you know well that they don't like it! It can be a very frustrating experience for the owner and stressful for the pet.

"What's somewhat surprising is that, if your pets see you popping a pill into your mouth and you accidentally drop it, they sometimes will race over and gobble it up before you have time to react. More commonly, dogs will find a prescription pill bottle, which makes a nice chew toy. If the dog happens to chew open the bottle, there are surprise treats inside.

"For some medications, even just one pill is enough to cause serious toxicity in a dog or cat. Medications designed to lower blood glucose in Type II diabetes, as well as those used to treat high blood pressure, can have devastating results when inadvertently eaten by dogs."

"Dogs will eat it if they find it! Depending on the amount ingested, dogs may become very agitated and hyperactive or, alternatively, they may become sedate. In either case, they need to be treated by a veterinarian who can administer a medication to hasten elimination of the toxin and other medications to counteract the adverse effects.

"The problem is that many pet owners are reluctant to tell a veterinarian that their dog got into some marijuana. But the reality is that the veterinarian's focus is on the welfare and health of the dog, and getting treatment needs to be a priority.

"Even when owners are reluctant to confess to the dog's exposure, the clinical signs that manifest can be very revealing. The classic one observed in most dogs after marijuana ingestion is dribbling urine."

"Lilies cause almost the same disease in cats as grapes do in dogs. Any part of the flower or plant can be toxic to cats. There are even reports of cats becoming sick and dying from walking through pollen dropped by lilies and grooming it off their paws, or drinking water from a vase that contains lilies. If you live with a cat, don't ever bring lilies into your home!"

"Reports of grape and raisin toxicity in dogs first appeared in the 1990s. Since then, there have been many confirmed cases, usually resulting in a dog's demise. The exact toxin and mechanism of toxicity has not yet been determined, so diagnosis relies on an owner's history of the exposure.

"I think that many, if not most, owners are still unaware that grapes and raisins are poisonous to dogs, partly because not every dog will get sick. And we can't yet predict which dogs will and which dogs won't get sick. Bottom line: Any grape or raisin exposure in a dog requires prompt veterinary care."

"Aflatoxin is a mycotoxin that can occur in grains like corn. If corn is grown or stored in specific temperature and humidity ranges, a mold can grow in it. The mold then produces a toxin that stays in the kernels. Even if the mold goes away, the toxin itself may remain.

"Each year, there are outbreaks of aflatoxicosis associated with kibbled dog foods that contain corn. In this case, it's not because the pet food manufacturers are doing anything wrong. Rather, it's because these mycotoxins can be difficult to detect. And since they can occur sporadically in a batch of corn, they can still find their way into pet food, even if it's properly tested before it's used."

"Onions and garlic belong to the genus Allium. These plants share a common toxic mechanism whereby they cause oxidative injury to cells — in particular, red blood cells. The sulfhydryl groups in hemoglobin are oxidized by sulfoxides that are present in all parts of the plant and bulbs.

"Cats have about twice as many sulfhydryl groups per hemoglobin molecule than dogs and other species, making them particularly sensitive to oxidative injury from Allium plants. Even a one-time small amount of garlic is enough to impair their ability to transport oxygen to tissues, causing injury to red blood cells that can last for months. In essence, it is a form of anemia in cats. If chronically exposed even to very low amounts over a long period of time, most cats will suffer signs of anemia."